Why saying “thanks” is so important?

Explanation:

because its a polite thing to do and its mannerism

Studies have confirmed that the simple act of saying 'thank you' can lead you to a happier life. When you express your thankfulness to others, it not only makes others feel great but also makes you feel great. It provides peace of mind and inner happiness.

Explanation:

b is the answer for this question.

the sentence that avoid faulty coordination is:

culture, which is well represented in philadelphia, plays a major role including theatre, music, and the visual arts.  

faulty coordination occurs when the writer gives equal importance two different ideas (clauses) which in fact are not equivalent. in order to correct a misplaced clause or idea, the writer can place less important or emphatic ideas in a relative clause as in the previous sentence.